Gregor Mendel - Austrian botanist, studied and described patterns of inheritance of traits.Mendel's laws - is the foundation of genetics still plays an important role in studying the influence of heredity and the transmission of hereditary characteristics.
In their experiments, the researchers crossed various types of peas differing in one alternative grounds: hue of colors, smooth-wrinkled pea stem height.In addition, a distinctive feature of Mendel's experiments was the use of so-called "clean lines", ieoffspring resulting from self-pollination of the parent plant.Mendel's laws, the wording and a brief description will be discussed below.
many years studying and meticulously preparing an experiment with peas: special bags protecting the flowers from external pollination, Austrian scientist has achieved incredible results at that time.A thorough and lengthy analysis of the data allowed the researcher to bring the laws of heredity, which later became known as "Mendel's laws".
Before proceeding to the description of the laws should be introduced several concepts necessary for the understanding of the text:
dominant gene - a gene whose symptoms manifest in the body.Represented by a capital letter: A, B. When the crossing is considered a sign of a stronger conditional, ieHe always manifested in the case if the second parent plant will be suspended at least weak signs.Which proves that the laws of Mendel.
recessive gene - gene is not expressed in the phenotype, although present in the genotype.Represented by a capital letter a, b.
heterozygous - hybrid, whose genotype (set of genes), there are dominant and recessive gene for a certain trait.(Aa or Bb)
homozygous - hybrid , has exclusively dominant or only recessive genes responsible for a trait.(AA or bb)
following Mendel's laws will be reviewed, summarized.
first law Mendel , also known as the law of the uniformity of hybrids, can be summarized as follows: the first generation of hybrids, we obtain from crossing pure lines paternal and maternal plants, it has no phenotypic (ie external) differences in the studied traits.In other words, all children have the same shade plants flowers, stem height, smoothness or roughness of peas.Moreover, it shows signs phenotypically corresponds exactly to the original grounds of one of the parents.
Second Law of Mendel's law of segregation or says, offspring of heterozygous hybrids in the first generation of self-pollination or inbreeding has both recessive and dominant traits.Wherein the cleavage takes place in the following way: 75% - the plants with the dominant feature, the remaining 25% - recessive.Simply put, if the parent plants had red flowers (dominant) and yellow flowers (recessive), the daughter plant will have a 3/4 red flowers, and the rest - yellow.
third and last law Mendel , which is also called the law of independent inheritance of characters, in general terms, means the following: when crossed homozygous plants have two or more different attributes (that is, for example, high plant with red flowers (AABB) and low plant with yellow flowers (aabb), studied traits (stem height and color of the flower) are inherited independently. In other words, the result of cross-breeding can become a tall plant with yellow flowers (Aabb) or low red (aaBb).
Mendel's lawsopened back in the mid-19th century, much later gained recognition. Based on them, built the whole of modern genetics, and after it - the selection. In addition, Mendel's laws are proof of the great diversity of species existing today.
